水洗和回烧工艺对高镍三元材料LiNi_(0.88)Co_(0.07)Al_(0.05)O_(2)微观结构及电化学性能的影响

Effect of Water Washing and Re-sintering Treatment on Microstructure and Electrochemical Properties of High Nickel Ternary Material LiNi_(0.88)Co_(0.07)Al_(0.05)O_(2)

以镍钴氢氧化物、异丙醇铝为原料,采用水解法合成三元前驱体Ni_(0.88)Co_(0.07)Al_(0.05)O_(2),再与锂盐混合烧结得到正极材料(TEM)、X射线光电子能谱(XPS)、能量色散X射线谱(EDS)和恒电流充放电测试等对样品的晶体结构、微观形貌、元素价态以及电化学性能进行表征。研究表明,料液比1∶25、水洗3次、600℃回烧2 h合成的LiNi_(0.88)Co_(0.07)Al_(0.05)O_(2)具有较优的综合电化学性能,其在0.2C的放电比容量达207.6 mAh·g^(-1),首次充放电效率为84.8%,1C放电比容量为192.0 mAh·g^(-1),循环100周后,材料的放电比容量仍有148.0 mAh·g^(-1),容量保持率达到77.1%。

Here,nickel cobalt hydroxide(Ni_(0.928)Co_(0.072)(OH)_(2))and aluminum isopropanol(C_(9)H_(21)AlO_(3))were used as raw material.The ternary precursor was synthesized by aluminum isopropanol hydrolysis.Then,the cathode materi-al LiNi_(0.88)Co_(0.07)Al_(0.05)O_(2) was obtained by mixing Ni_(0.928)Co_(0.072)(OH)_(2) with lithium salt and subsequent sintering.After washing and re-sintering,the crystal structure,microstructure and electrochemical properties of the target products were characterized by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectronic spectroscopy(XPS),energy dispersive X-ray spectroscopy(EDS),transmission electron microscope(TEM)and elec-trochemical tests.The results showed that synthesized LiNi_(0.88)Co_(0.07)Al_(0.05)O_(2) had better comprehensive electrochemi-cal performance when the ratio of solid to liquid was 1∶25,washed with deionized water for three times and calcined at 600℃for 2 h.The specific discharge capacity of 0.2 C was up to 207.6 mAh·g^(-1),the first charge and discharge efficiency was 84.8%,and the specific discharge capacity of 1 C was 192.0 mAh·g^(-1).After 100 cycles,the specific discharge capacity of the material was still 148.0 mAh·g^(-1),and the capacity retention rate reached 77.1%.